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Ingy döt Net 2023-07-01 11:58:00 -04:00
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2
Task/Word-ladder/00-META.yaml Normal file
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---
from: http://rosettacode.org/wiki/Word_ladder

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Task/Word-ladder/00-TASK.txt Normal file
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Yet another shortest path problem. Given two words of equal length the task is to transpose the first into the second.
Only one letter may be changed at a time and the change must result in a word in [http://wiki.puzzlers.org/pub/wordlists/unixdict.txt unixdict], the minimum number of intermediate words should be used.
Demonstrate the following:
A boy can be made into a man: boy -> bay -> ban -> man
With a little more difficulty a girl can be made into a lady: girl -> gill -> gall -> gale -> gaze -> laze -> lazy -> lady
A john can be made into a jane: john -> cohn -> conn -> cone -> cane -> jane
A child can not be turned into an adult.
Optional transpositions of your choice.
{{Template:Strings}}
<br><br>

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Task/Word-ladder/11l/word-ladder.11l Normal file
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F isOneAway(word1, word2)
V result = 0B
L(i) 0 .< word1.len
I word1[i] != word2[i]
I result
R 0B
E
result = 1B
R result
DefaultDict[Int, [String]] words
L(word) File(‘unixdict.txt’).read().split("\n")
words[word.len] [+]= word
F find_path(start, target)
V lg = start.len
assert(target.len == lg, ‘Source and destination must have same length.’)
assert(start C :words[lg], ‘Source must exist in the dictionary.’)
assert(target C :words[lg], ‘Destination must exist in the dictionary.’)
V currPaths = [[start]]
V pool = copy(:words[lg])
L
[[String]] newPaths
[String] added
L(candidate) pool
L(path) currPaths
I isOneAway(candidate, path.last)
V newPath = path [+] [candidate]
I candidate == target
R newPath
E
newPaths.append(newPath)
added.append(candidate)
L.break
I newPaths.empty
L.break
currPaths = move(newPaths)
L(w) added
pool.remove(w)
R [String]()
L(start, target) [(‘boy’, ‘man’), (‘girl’, ‘lady’), (‘john’, ‘jane’), (‘child’, ‘adult’), (‘cat’, ‘dog’), (‘lead’, ‘gold’), (‘white’, ‘black’), (‘bubble’, ‘tickle’)]
V path = find_path(start, target)
I path.empty
print(‘No path from "’start‘" to "’target‘".’)
E
print(path.join(‘ -> ’))

179
Task/Word-ladder/ALGOL-68/word-ladder.alg Normal file
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# quick implementation of a stack of INT.
real program starts after it.
#
MODE STACK = STRUCT (INT top, FLEX[1:0]INT data, INT increment);
PROC makestack = (INT increment)STACK: (1, (), increment);
PROC pop = (REF STACK s)INT: ( top OF s -:= 1; (data OF s)[top OF s] );
PROC push = (REF STACK s, INT n)VOID:
BEGIN
IF top OF s > UPB data OF s THEN
[ UPB data OF s + increment OF s ]INT tmp;
tmp[1 : UPB data OF s] := data OF s;
data OF s := tmp
FI;
(data OF s)[top OF s] := n;
top OF s +:= 1
END;
PROC empty = (REF STACK s)BOOL: top OF s <= 1;
PROC contents = (REF STACK s)[]INT: (data OF s)[:top OF s - 1];
# start solution #
[]STRING words = BEGIN # load dictionary file into array #
FILE f;
BOOL eof := FALSE;
open(f, "unixdict.txt", stand in channel);
on logical file end(f, (REF FILE f)BOOL: eof := TRUE);
INT idx := 1;
FLEX [1:0] STRING words;
STRING word;
WHILE NOT eof DO
get(f, (word, newline));
IF idx > UPB words THEN
HEAP [1 : UPB words + 10000]STRING tmp;
tmp[1 : UPB words] := words;
words := tmp
FI;
words[idx] := word;
idx +:= 1
OD;
words[1:idx-1]
END;
INT nwords = UPB words;
INT max word length = (INT mwl := 0;
FOR i TO UPB words DO
IF mwl < UPB words[i] THEN mwl := UPB words[i] FI
OD;
mwl);
[nwords]FLEX[0]INT neighbors;
[max word length]BOOL precalculated by length;
FOR i TO UPB precalculated by length DO precalculated by length[i] := FALSE OD;
# precalculating neighbours takes time, but not doing it is even slower... #
PROC precalculate neighbors = (INT word length)VOID:
BEGIN
[nwords]REF STACK stacks;
FOR i TO UPB stacks DO stacks[i] := NIL OD;
FOR i TO UPB words DO
IF UPB words[i] = word length THEN
IF REF STACK(stacks[i]) :=: NIL THEN stacks[i] := HEAP STACK := makestack(10) FI;
FOR j FROM i + 1 TO UPB words DO
IF UPB words[j] = word length THEN
IF neighboring(words[i], words[j]) THEN
push(stacks[i], j);
IF REF STACK(stacks[j]) :=: NIL THEN stacks[j] := HEAP STACK := makestack(10) FI;
push(stacks[j], i)
FI
FI
OD
FI
OD;
FOR i TO UPB neighbors DO
IF REF STACK(stacks[i]) :/=: NIL THEN
neighbors[i] := contents(stacks[i])
FI
OD;
precalculated by length [word length] := TRUE
END;
PROC neighboring = (STRING a, b)BOOL: # do a & b differ in just 1 char? #
BEGIN
INT diff := 0;
FOR i TO UPB a DO IF a[i] /= b[i] THEN diff +:= 1 FI OD;
diff = 1
END;
PROC word ladder = (STRING from, STRING to)[]STRING:
BEGIN
IF UPB from /= UPB to THEN fail FI;
INT word length = UPB from;
IF word length < 1 OR word length > max word length THEN fail FI;
IF from = to THEN fail FI;
INT start := 0;
INT destination := 0;
FOR i TO UPB words DO
IF UPB words[i] = word length THEN
IF words[i] = from THEN start := i
ELIF words[i] = to THEN destination := i
FI
FI
OD;
IF destination = 0 OR start = 0 THEN fail FI;
IF NOT precalculated by length [word length] THEN
precalculate neighbors(word length)
FI;
STACK stack := makestack(1000);
[nwords]INT distance;
[nwords]INT previous;
FOR i TO nwords DO distance[i] := nwords+1; previous[i] := 0 OD;
INT shortest := nwords+1;
distance[start] := 0;
push(stack, start);
WHILE NOT empty(stack)
DO
INT curr := pop(stack);
INT dist := distance[curr];
IF dist < shortest - 1 THEN
# find neighbors and add them to the stack #
FOR i FROM UPB neighbors[curr] BY -1 TO 1 DO
INT n = neighbors[curr][i];
IF distance[n] > dist + 1 THEN
distance[n] := dist + 1;
previous[n] := curr;
IF n = destination THEN
shortest := dist + 1
ELSE
push(stack, n)
FI
FI
OD;
IF curr = destination THEN shortest := dist FI
FI
OD;
INT length = distance[destination] + 1;
IF length > nwords THEN fail FI;
[length]STRING result;
INT curr := destination;
FOR i FROM length BY -1 TO 1
DO
result[i] := words[curr];
curr := previous[curr]
OD;
result EXIT
fail: LOC [0] STRING
END;
[][]STRING pairs = (("boy", "man"), ("bed", "cot"),
("old", "new"), ("dry", "wet"),
("girl", "lady"), ("john", "jane"),
("lead", "gold"), ("poor", "rich"),
("lamb", "stew"), ("kick", "goal"),
("cold", "warm"), ("nude", "clad"),
("child", "adult"), ("white", "black"),
("bread", "toast"), ("lager", "stout"),
("bride", "groom"), ("table", "chair"),
("bubble", "tickle"));
FOR i TO UPB pairs
DO
STRING from = pairs[i][1], to = pairs[i][2];
[]STRING ladder = word ladder(from, to);
IF UPB ladder = 0
THEN print(("No solution for """ + from + """ -> """ + to + """", newline))
ELSE FOR j TO UPB ladder DO print(((j > 1 | "->" | ""), ladder[j])) OD;
print(newline)
FI
OD

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Task/Word-ladder/C++/word-ladder.cpp Normal file
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#include <algorithm>
#include <fstream>
#include <iostream>
#include <map>
#include <string>
#include <vector>
using word_map = std::map<size_t, std::vector<std::string>>;
// Returns true if strings s1 and s2 differ by one character.
bool one_away(const std::string& s1, const std::string& s2) {
if (s1.size() != s2.size())
return false;
bool result = false;
for (size_t i = 0, n = s1.size(); i != n; ++i) {
if (s1[i] != s2[i]) {
if (result)
return false;
result = true;
}
}
return result;
}
// Join a sequence of strings into a single string using the given separator.
template <typename iterator_type, typename separator_type>
std::string join(iterator_type begin, iterator_type end,
separator_type separator) {
std::string result;
if (begin != end) {
result += *begin++;
for (; begin != end; ++begin) {
result += separator;
result += *begin;
}
}
return result;
}
// If possible, print the shortest chain of single-character modifications that
// leads from "from" to "to", with each intermediate step being a valid word.
// This is an application of breadth-first search.
bool word_ladder(const word_map& words, const std::string& from,
const std::string& to) {
auto w = words.find(from.size());
if (w != words.end()) {
auto poss = w->second;
std::vector<std::vector<std::string>> queue{{from}};
while (!queue.empty()) {
auto curr = queue.front();
queue.erase(queue.begin());
for (auto i = poss.begin(); i != poss.end();) {
if (!one_away(*i, curr.back())) {
++i;
continue;
}
if (to == *i) {
curr.push_back(to);
std::cout << join(curr.begin(), curr.end(), " -> ") << '\n';
return true;
}
std::vector<std::string> temp(curr);
temp.push_back(*i);
queue.push_back(std::move(temp));
i = poss.erase(i);
}
}
}
std::cout << from << " into " << to << " cannot be done.\n";
return false;
}
int main() {
word_map words;
std::ifstream in("unixdict.txt");
if (!in) {
std::cerr << "Cannot open file unixdict.txt.\n";
return EXIT_FAILURE;
}
std::string word;
while (getline(in, word))
words[word.size()].push_back(word);
word_ladder(words, "boy", "man");
word_ladder(words, "girl", "lady");
word_ladder(words, "john", "jane");
word_ladder(words, "child", "adult");
word_ladder(words, "cat", "dog");
word_ladder(words, "lead", "gold");
word_ladder(words, "white", "black");
word_ladder(words, "bubble", "tickle");
return EXIT_SUCCESS;
}

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Task/Word-ladder/F-Sharp/word-ladder-1.fs Normal file
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// Word ladder: Nigel Galloway. June 5th., 2021
let fG n g=n|>List.partition(fun n->2>Seq.fold2(fun z n g->z+if n=g then 0 else 1) 0 n g)
let wL n g=let dict=seq{use n=System.IO.File.OpenText("unixdict.txt") in while not n.EndOfStream do yield n.ReadLine()}|>Seq.filter(Seq.length>>(=)(Seq.length n))|>List.ofSeq|>List.except [n]
let (|Done|_|) n=n|>List.tryFind((=)g)
let rec wL n g l=match n with h::t->let i,e=fG l (List.head h) in match i with Done i->Some((i::h)|>List.rev) |_->wL t ((i|>List.map(fun i->i::h))@g) e
|_->match g with []->None |_->wL g [] l
let i,e=fG dict n in match i with Done i->Some([n;g]) |_->wL(i|>List.map(fun g->[g;n])) [] e
[("boy","man");("girl","lady");("john","jane");("child","adult")]|>List.iter(fun(n,g)->printfn "%s" (match wL n g with Some n->n|>String.concat " -> " |_->n+" into "+g+" can't be done"))

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Task/Word-ladder/F-Sharp/word-ladder-2.fs Normal file
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[("evil","good");("god","man")]|>List.iter(fun(n,g)->printfn "%s" (match wL n g with Some n->n|>String.concat " -> " |_->n+" into "+g+" can't be done"))

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Task/Word-ladder/Go/word-ladder.go Normal file
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package main
import (
"bytes"
"fmt"
"io/ioutil"
"log"
"strings"
)
func contains(a []string, s string) bool {
for _, e := range a {
if e == s {
return true
}
}
return false
}
func oneAway(a, b string) bool {
sum := 0
for i := 0; i < len(a); i++ {
if a[i] != b[i] {
sum++
}
}
return sum == 1
}
func wordLadder(words []string, a, b string) {
l := len(a)
var poss []string
for _, word := range words {
if len(word) == l {
poss = append(poss, word)
}
}
todo := [][]string{{a}}
for len(todo) > 0 {
curr := todo[0]
todo = todo[1:]
var next []string
for _, word := range poss {
if oneAway(word, curr[len(curr)-1]) {
next = append(next, word)
}
}
if contains(next, b) {
curr = append(curr, b)
fmt.Println(strings.Join(curr, " -> "))
return
}
for i := len(poss) - 1; i >= 0; i-- {
if contains(next, poss[i]) {
copy(poss[i:], poss[i+1:])
poss[len(poss)-1] = ""
poss = poss[:len(poss)-1]
}
}
for _, s := range next {
temp := make([]string, len(curr))
copy(temp, curr)
temp = append(temp, s)
todo = append(todo, temp)
}
}
fmt.Println(a, "into", b, "cannot be done.")
}
func main() {
b, err := ioutil.ReadFile("unixdict.txt")
if err != nil {
log.Fatal("Error reading file")
}
bwords := bytes.Fields(b)
words := make([]string, len(bwords))
for i, bword := range bwords {
words[i] = string(bword)
}
pairs := [][]string{
{"boy", "man"},
{"girl", "lady"},
{"john", "jane"},
{"child", "adult"},
}
for _, pair := range pairs {
wordLadder(words, pair[0], pair[1])
}
}

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Task/Word-ladder/Haskell/word-ladder-1.hs Normal file
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import System.IO (readFile)
import Control.Monad (foldM)
import Data.List (intercalate)
import qualified Data.Set as S
distance :: String -> String -> Int
distance s1 s2 = length $ filter not $ zipWith (==) s1 s2
wordLadders :: [String] -> String -> String -> [[String]]
wordLadders dict start end
| length start /= length end = []
| otherwise = [wordSpace] >>= expandFrom start >>= shrinkFrom end
where
wordSpace = S.fromList $ filter ((length start ==) . length) dict
expandFrom s = go [[s]]
where
go (h:t) d
| S.null d || S.null f = []
| end `S.member` f = [h:t]
| otherwise = go (S.elems f:h:t) (d S.\\ f)
where
f = foldr (\w -> S.union (S.filter (oneStepAway w) d)) mempty h
shrinkFrom = scanM (filter . oneStepAway)
oneStepAway x = (1 ==) . distance x
scanM f x = fmap snd . foldM g (x,[x])
where g (b, r) a = (\x -> (x, x:r)) <$> f b a
wordLadder :: [String] -> String -> String -> [String]
wordLadder d s e = case wordLadders d s e of
[] -> []
h:_ -> h
showChain [] = putStrLn "No chain"
showChain ch = putStrLn $ intercalate " -> " ch
main = do
dict <- lines <$> readFile "unixdict.txt"
showChain $ wordLadder dict "boy" "man"
showChain $ wordLadder dict "girl" "lady"
showChain $ wordLadder dict "john" "jane"
showChain $ wordLadder dict "alien" "drool"
showChain $ wordLadder dict "child" "adult"

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Task/Word-ladder/Haskell/word-ladder-2.hs Normal file
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wordLadders2 :: String -> String -> [String] -> [[String]]
wordLadders2 start end dict
| length start /= length end = []
| otherwise = pure wordSpace >>= expand start end >>= shrink end
where
wordSpace = S.fromList $ filter ((length start ==) . length) dict
expand s e d = tail . map S.elems <$> go [S.singleton s] [S.singleton e] d
where
go (hs:ts) (he:te) d
| S.null d || S.null fs || S.null fe = []
| not $ S.null f1 = [reverse (f1:te) ++ hs:ts]
| not $ S.null f2 = [reverse (he:te) ++ f2:ts]
| not $ S.null f3 = [reverse (he:te) ++ f3:hs:ts]
| otherwise = go (fs:hs:ts) (fe:he:te) (d S.\\ hs S.\\ he)
where
fs = front hs
fe = front he
f1 = fs `S.intersection` he
f2 = fe `S.intersection` hs
f3 = fs `S.intersection` fe
front = S.foldr (\w -> S.union (S.filter (oneStepAway w) d)) mempty
shrink = scanM (findM . oneStepAway)
oneStepAway x = (1 ==) . distance x
scanM f x = fmap snd . foldM g (x,[x])
where g (b, r) a = (\x -> (x, x:r)) <$> f b a
findM p = msum . map (\x -> if p x then pure x else mzero)

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Task/Word-ladder/Haskell/word-ladder-3.hs Normal file
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import AStar (findPath, Graph(..))
import qualified Data.Map as M
distance :: String -> String -> Int
distance s1 s2 = length $ filter not $ zipWith (==) s1 s2
wordLadder :: [String] -> String -> String -> [String]
wordLadder dict start end = findPath g distance start end
where
short_dict = filter ((length start ==) . length) dict
g = Graph $ \w -> M.fromList [ (x, 1)
| x <- short_dict
, distance w x == 1 ]

30
Task/Word-ladder/J/word-ladder-1.j Normal file
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extend=: {{
j=. {:y
l=. <:{:$m
<y,"1 0 I.l=m+/ .="1 j{m
}}
wlad=: {{
l=. #x assert. l=#y
words=. >(#~ l=#@>) cutLF fread 'unixdict.txt'
ix=. ,:words i.x assert. ix<#words
iy=. ,:words i.y assert. iy<#words
while. -. 1 e. ix e.&, iy do.
if. 0 e. ix,&# iy do. EMPTY return. end.
ix=. ; words extend"1 ix
if. -. 1 e. ix e.&, iy do.
iy=. ; words extend"1 iy
end.
end.
iy=. |."1 iy
r=. ix,&,iy
for_jk.(ix,&#iy)#:I.,ix +./@e."1/ iy do.
ixj=. ({.jk){ix
iyk=. ({:jk){iy
for_c. ixj ([-.-.) iyk do.
path=. (ixj{.~ixj i.c) , iyk}.~ iyk i.c
if. path <&# r do. r=. path end.
end.
end.
}.,' ',.r{words
}}

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Task/Word-ladder/J/word-ladder-2.j Normal file
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'boy' wlad 'man'
boy bay ban man
'girl' wlad 'lady'
girl gill gall gale gaze laze lazy lady
'john' wlad 'jane'
john cohn conn cone cane jane
'child' wlad 'adult'
'cat' wlad 'dog'
cat cot cog dog
'lead' wlad 'gold'
lead load goad gold
'white' wlad 'black'
white whine chine chink clink blink blank black
'bubble' wlad 'tickle'
bubble babble gabble garble gargle gaggle giggle jiggle jingle tingle tinkle tickle

94
Task/Word-ladder/Java/word-ladder-1.java Normal file
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import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.PriorityQueue;
import java.util.Set;
import java.util.stream.IntStream;
public class WordLadder {
private static int distance(String s1, String s2) {
assert s1.length() == s2.length();
return (int) IntStream.range(0, s1.length())
.filter(i -> s1.charAt(i) != s2.charAt(i))
.count();
}
private static void wordLadder(Map<Integer, Set<String>> words, String fw, String tw) {
wordLadder(words, fw, tw, 8);
}
private static void wordLadder(Map<Integer, Set<String>> words, String fw, String tw, int limit) {
if (fw.length() != tw.length()) {
throw new IllegalArgumentException("From word and to word must have the same length");
}
Set<String> ws = words.get(fw.length());
if (ws.contains(fw)) {
List<String> primeList = new ArrayList<>();
primeList.add(fw);
PriorityQueue<List<String>> queue = new PriorityQueue<>((chain1, chain2) -> {
int cmp1 = Integer.compare(chain1.size(), chain2.size());
if (cmp1 == 0) {
String last1 = chain1.get(chain1.size() - 1);
int d1 = distance(last1, tw);
String last2 = chain2.get(chain2.size() - 1);
int d2 = distance(last2, tw);
return Integer.compare(d1, d2);
}
return cmp1;
});
queue.add(primeList);
while (queue.size() > 0) {
List<String> curr = queue.remove();
if (curr.size() > limit) {
continue;
}
String last = curr.get(curr.size() - 1);
for (String word : ws) {
if (distance(last, word) == 1) {
if (word.equals(tw)) {
curr.add(word);
System.out.println(String.join(" -> ", curr));
return;
}
if (!curr.contains(word)) {
List<String> cp = new ArrayList<>(curr);
cp.add(word);
queue.add(cp);
}
}
}
}
}
System.err.printf("Cannot turn `%s` into `%s`%n", fw, tw);
}
public static void main(String[] args) throws IOException {
Map<Integer, Set<String>> words = new HashMap<>();
for (String line : Files.readAllLines(Path.of("unixdict.txt"))) {
Set<String> wl = words.computeIfAbsent(line.length(), HashSet::new);
wl.add(line);
}
wordLadder(words, "boy", "man");
wordLadder(words, "girl", "lady");
wordLadder(words, "john", "jane");
wordLadder(words, "child", "adult");
wordLadder(words, "cat", "dog");
wordLadder(words, "lead", "gold");
wordLadder(words, "white", "black");
wordLadder(words, "bubble", "tickle", 12);
}
}

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Task/Word-ladder/Java/word-ladder-2.java Normal file
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import java.io.*;
import java.util.*;
public class WordLadder {
public static void main(String[] args) {
try {
Map<Integer, List<String>> words = new HashMap<>();
try (BufferedReader reader = new BufferedReader(new FileReader("unixdict.txt"))) {
String line;
while ((line = reader.readLine()) != null)
words.computeIfAbsent(line.length(), k -> new ArrayList<String>()).add(line);
}
wordLadder(words, "boy", "man");
wordLadder(words, "girl", "lady");
wordLadder(words, "john", "jane");
wordLadder(words, "child", "adult");
wordLadder(words, "cat", "dog");
wordLadder(words, "lead", "gold");
wordLadder(words, "white", "black");
wordLadder(words, "bubble", "tickle");
} catch (Exception e) {
e.printStackTrace();
}
}
// Returns true if strings s1 and s2 differ by one character.
private static boolean oneAway(String s1, String s2) {
if (s1.length() != s2.length())
return false;
boolean result = false;
for (int i = 0, n = s1.length(); i != n; ++i) {
if (s1.charAt(i) != s2.charAt(i)) {
if (result)
return false;
result = true;
}
}
return result;
}
// If possible, print the shortest chain of single-character modifications that
// leads from "from" to "to", with each intermediate step being a valid word.
// This is an application of breadth-first search.
private static void wordLadder(Map<Integer, List<String>> words, String from, String to) {
List<String> w = words.get(from.length());
if (w != null) {
Deque<String> poss = new ArrayDeque<>(w);
Deque<String> f = new ArrayDeque<String>();
f.add(from);
Deque<Deque<String>> queue = new ArrayDeque<>();
queue.add(f);
while (!queue.isEmpty()) {
Deque<String> curr = queue.poll();
for (Iterator<String> i = poss.iterator(); i.hasNext(); ) {
String str = i.next();
if (!oneAway(str, curr.getLast()))
continue;
if (to.equals(str)) {
curr.add(to);
System.out.println(String.join(" -> ", curr));
return;
}
Deque<String> temp = new ArrayDeque<>(curr);
temp.add(str);
queue.add(temp);
i.remove();
}
}
}
System.out.printf("%s into %s cannot be done.\n", from, to);
}
}

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def count(stream): reduce stream as $i (0; .+1);
def words: [inputs]; # one way to read the word list
def oneAway($a; $b):
($a|explode) as $ax
| ($b|explode) as $bx
| 1 == count(range(0; $a|length) | select($ax[.] != $bx[.]));
# input: the word list
def wordLadder($a; $b):
($a|length) as $len
| { poss: map(select(length == $len)), # the relevant words
todo: [[$a]] # possible chains
}
| until ( ((.todo|length) == 0) or .solution;
.curr = .todo[0]
| .todo |= .[1:]
| .curr[-1] as $c
| (.poss | map(select( oneAway(.; $c) ))) as $next
| if ($b | IN($next[]))
then .curr += [$b]
| .solution = (.curr|join(" -> "))
else .poss = (.poss - $next)
| .curr as $curr
| .todo = (reduce range(0; $next|length) as $i (.todo;
. + [$curr + [$next[$i] ]] ))
end )
| if .solution then .solution
else "There is no ladder from \($a) to \($b)."
end ;
def pairs:
["boy", "man"],
["girl", "lady"],
["john", "jane"],
["child", "adult"],
["word", "play"]
;
words
| pairs as $p
| wordLadder($p[0]; $p[1])

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Task/Word-ladder/Julia/word-ladder.julia Normal file
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const dict = Set(split(read("unixdict.txt", String), r"\s+"))
function targeted_mutations(str::AbstractString, target::AbstractString)
working, tried = [[str]], Set{String}()
while all(a -> a[end] != target, working)
newworking = Vector{Vector{String}}()
for arr in working
s = arr[end]
push!(tried, s)
for j in 1:length(s), c in 'a':'z'
w = s[1:j-1] * c * s[j+1:end]
if w in dict && !(w in tried)
push!(newworking, [arr; w])
end
end
end
isempty(newworking) && return [["This cannot be done."]]
working = newworking
end
return filter(a -> a[end] == target, working)
end
println("boy to man: ", targeted_mutations("boy", "man"))
println("girl to lady: ", targeted_mutations("girl", "lady"))
println("john to jane: ", targeted_mutations("john", "jane"))
println("child to adult: ", targeted_mutations("child", "adult"))

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Task/Word-ladder/Mathematica/word-ladder.math Normal file
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db=DeleteDuplicates[RemoveDiacritics[ToLowerCase[Select[DictionaryLookup[],StringLength/*EqualTo[3]]]]];
sel=Select[Subsets[db,{2}],HammingDistance[#[[1]],#[[2]]]==1&];
g=Graph[db,UndirectedEdge@@@sel];
FindShortestPath[g,"boy","man"]
db=DeleteDuplicates[RemoveDiacritics[ToLowerCase[Select[DictionaryLookup[],StringLength/*EqualTo[4]]]]];
sel=Select[Subsets[db,{2}],HammingDistance[#[[1]],#[[2]]]==1&];
g=Graph[db,UndirectedEdge@@@sel];
FindShortestPath[g,"girl","lady"]
FindShortestPath[g,"john","jane"]
db=DeleteDuplicates[RemoveDiacritics[ToLowerCase[Select[DictionaryLookup[],StringLength/*EqualTo[5]]]]];
sel=Select[Subsets[db,{2}],HammingDistance[#[[1]],#[[2]]]==1&];
g=Graph[db,UndirectedEdge@@@sel];
FindShortestPath[g,"child","adult"]

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Task/Word-ladder/Nim/word-ladder.nim Normal file
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import sets, strformat, strutils
func isOneAway(word1, word2: string): bool =
## Return true if "word1" and "word2" has only one letter of difference.
for i in 0..word1.high:
if word1[i] != word2[i]:
if result: return false # More than one letter of difference.
else: result = true # One letter of difference, for now.
var words: array[1..22, HashSet[string]] # Set of words sorted by length.
for word in "unixdict.txt".lines:
words[word.len].incl word
proc path(start, target: string): seq[string] =
## Return a path from "start" to "target" or an empty list
## if there is no possible path.
let lg = start.len
doAssert target.len == lg, "Source and destination must have same length."
doAssert start in words[lg], "Source must exist in the dictionary."
doAssert target in words[lg], "Destination must exist in the dictionary."
var currPaths = @[@[start]] # Current list of paths found.
var pool = words[lg] # List of possible words to use.
while true:
var newPaths: seq[seq[string]] # Next list of paths.
var added: HashSet[string] # Set of words added during the round.
for candidate in pool:
for path in currPaths:
if candidate.isOneAway(path[^1]):
let newPath = path & candidate
if candidate == target:
# Found a path.
return newPath
else:
# Not the target. Add a new path.
newPaths.add newPath
added.incl candidate
break
if newPaths.len == 0: break # No path.
currPaths = move(newPaths) # Update list of paths.
pool.excl added # Remove added words from pool.
when isMainModule:
for (start, target) in [("boy", "man"), ("girl", "lady"), ("john", "jane"),
("child", "adult"), ("cat", "dog"), ("lead", "gold"),
("white", "black"), ("bubble", "tickle")]:
let path = path(start, target)
if path.len == 0:
echo &"No path from “{start}” to “{target}”."
else:
echo path.join(" → ")

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use strict;
use warnings;
my %dict;
open my $handle, '<', 'unixdict.txt';
while (my $word = <$handle>) {
chomp($word);
my $len = length $word;
if (exists $dict{$len}) {
push @{ $dict{ $len } }, $word;
} else {
my @words = ( $word );
$dict{$len} = \@words;
}
}
close $handle;
sub distance {
my $w1 = shift;
my $w2 = shift;
my $dist = 0;
for my $i (0 .. length($w1) - 1) {
my $c1 = substr($w1, $i, 1);
my $c2 = substr($w2, $i, 1);
if (not ($c1 eq $c2)) {
$dist++;
}
}
return $dist;
}
sub contains {
my $aref = shift;
my $needle = shift;
for my $v (@$aref) {
if ($v eq $needle) {
return 1;
}
}
return 0;
}
sub word_ladder {
my $fw = shift;
my $tw = shift;
if (exists $dict{length $fw}) {
my @poss = @{ $dict{length $fw} };
my @queue = ([$fw]);
while (scalar @queue > 0) {
my $curr_ref = shift @queue;
my $last = $curr_ref->[-1];
my @next;
for my $word (@poss) {
if (distance($last, $word) == 1) {
push @next, $word;
}
}
if (contains(\@next, $tw)) {
push @$curr_ref, $tw;
print join (' -> ', @$curr_ref), "\n";
return;
}
for my $word (@next) {
for my $i (0 .. scalar @poss - 1) {
if ($word eq $poss[$i]) {
splice @poss, $i, 1;
last;
}
}
}
for my $word (@next) {
my @temp = @$curr_ref;
push @temp, $word;
push @queue, \@temp;
}
}
}
print STDERR "Cannot change $fw into $tw\n";
}
word_ladder('boy', 'man');
word_ladder('girl', 'lady');
word_ladder('john', 'jane');
word_ladder('child', 'adult');
word_ladder('cat', 'dog');
word_ladder('lead', 'gold');
word_ladder('white', 'black');
word_ladder('bubble', 'tickle');

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Task/Word-ladder/Perl/word-ladder-2.pl Normal file
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use strict;
use warnings;
use feature 'say';
my %dict;
open my $handle, '<', 'ref/unixdict.txt';
while (my $word = <$handle>) {
chomp $word;
my $l = length $word;
if ($dict{$l}) { push @{ $dict{$l} }, $word }
else { $dict{$l} = \@{[$word]} }
}
close $handle;
sub distance {
my($w1,$w2) = @_;
my $d;
substr($w1, $_, 1) eq substr($w2, $_, 1) or $d++ for 0 .. length($w1) - 1;
return $d // 0;
}
sub contains {
my($aref,$needle) = @_;
$needle eq $_ and return 1 for @$aref;
return 0;
}
sub word_ladder {
my($fw,$tw) = @_;
say 'Nothing like that in dictionary.' and return unless $dict{length $fw};
my @poss = @{ $dict{length $fw} };
my @queue = [$fw];
while (@queue) {
my $curr_ref = shift @queue;
my $last = $curr_ref->[-1];
my @next;
distance($last, $_) == 1 and push @next, $_ for @poss;
push(@$curr_ref, $tw) and say join ' -> ', @$curr_ref and return if contains \@next, $tw;
for my $word (@next) {
$word eq $poss[$_] and splice(@poss, $_, 1) and last for 0 .. @poss - 1;
}
push @queue, \@{[@{$curr_ref}, $_]} for @next;
}
say "Cannot change $fw into $tw";
}
word_ladder(split) for 'boy man', 'girl lady', 'john jane', 'child adult';

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Task/Word-ladder/Phix/word-ladder.phix Normal file
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(phixonline)-->
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">words</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">unix_dict</span><span style="color: #0000FF;">()</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">right_length</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">word</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">integer</span> <span style="color: #000000;">l</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">return</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">word</span><span style="color: #0000FF;">)=</span><span style="color: #000000;">l</span> <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">one_away</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">return</span> <span style="color: #7060A8;">sum</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sq_ne</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">))=</span><span style="color: #000000;">1</span> <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">dca</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">return</span> <span style="color: #7060A8;">append</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">deep_copy</span><span style="color: #0000FF;">(</span><span style="color: #000000;">s</span><span style="color: #0000FF;">),</span><span style="color: #000000;">n</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">word_ladder</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">a</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">b</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">poss</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">filter</span><span style="color: #0000FF;">(</span><span style="color: #000000;">words</span><span style="color: #0000FF;">,</span><span style="color: #000000;">right_length</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">)),</span>
<span style="color: #000000;">todo</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{{</span><span style="color: #000000;">a</span><span style="color: #0000FF;">}},</span>
<span style="color: #000000;">curr</span> <span style="color: #000080;font-style:italic;">-- aka todo[1], word chain starting from a</span>
<span style="color: #008080;">while</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">todo</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
<span style="color: #0000FF;">{</span><span style="color: #000000;">curr</span><span style="color: #0000FF;">,</span><span style="color: #000000;">todo</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{</span><span style="color: #000000;">todo</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">],</span><span style="color: #000000;">todo</span><span style="color: #0000FF;">[</span><span style="color: #000000;">2</span><span style="color: #0000FF;">..$]}</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">next</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">filter</span><span style="color: #0000FF;">(</span><span style="color: #000000;">poss</span><span style="color: #0000FF;">,</span><span style="color: #000000;">one_away</span><span style="color: #0000FF;">,</span><span style="color: #000000;">curr</span><span style="color: #0000FF;">[$])</span>
<span style="color: #008080;">if</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">b</span><span style="color: #0000FF;">,</span><span style="color: #000000;">next</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">then</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"%s\n"</span><span style="color: #0000FF;">,{</span><span style="color: #7060A8;">join</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">append</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">deep_copy</span><span style="color: #0000FF;">(</span><span style="color: #000000;">curr</span><span style="color: #0000FF;">),</span><span style="color: #000000;">b</span><span style="color: #0000FF;">),</span><span style="color: #008000;">"-&gt;"</span><span style="color: #0000FF;">)})</span>
<span style="color: #008080;">return</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #000000;">poss</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">filter</span><span style="color: #0000FF;">(</span><span style="color: #000000;">poss</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"out"</span><span style="color: #0000FF;">,</span><span style="color: #000000;">next</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">todo</span> <span style="color: #0000FF;">&=</span> <span style="color: #7060A8;">apply</span><span style="color: #0000FF;">(</span><span style="color: #004600;">true</span><span style="color: #0000FF;">,</span><span style="color: #000000;">dca</span><span style="color: #0000FF;">,{{</span><span style="color: #000000;">curr</span><span style="color: #0000FF;">},</span><span style="color: #000000;">next</span><span style="color: #0000FF;">})</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"%s into %s cannot be done\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">a</span><span style="color: #0000FF;">,</span><span style="color: #000000;">b</span><span style="color: #0000FF;">})</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #000000;">word_ladder</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"boy"</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"man"</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">word_ladder</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"girl"</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"lady"</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">word_ladder</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"john"</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"jane"</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">word_ladder</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"child"</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"adult"</span><span style="color: #0000FF;">)</span>
<!--

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Task/Word-ladder/Python/word-ladder.py Normal file
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import os,sys,zlib,urllib.request
def h ( str,x=9 ):
for c in str :
x = ( x*33 + ord( c )) & 0xffffffffff
return x
def cache ( func,*param ):
n = 'cache_%x.bin'%abs( h( repr( param )))
try : return eval( zlib.decompress( open( n,'rb' ).read()))
except : pass
s = func( *param )
open( n,'wb' ).write( zlib.compress( bytes( repr( s ),'ascii' )))
return s
dico_url = 'https://raw.githubusercontent.com/quinnj/Rosetta-Julia/master/unixdict.txt'
read_url = lambda url : urllib.request.urlopen( url ).read()
load_dico = lambda url : tuple( cache( read_url,url ).split( b'\n'))
isnext = lambda w1,w2 : len( w1 ) == len( w2 ) and len( list( filter( lambda l : l[0]!=l[1] , zip( w1,w2 )))) == 1
def build_map ( words ):
map = [(w.decode('ascii'),[]) for w in words]
for i1,(w1,n1) in enumerate( map ):
for i2,(w2,n2) in enumerate( map[i1+1:],i1+1 ):
if isnext( w1,w2 ):
n1.append( i2 )
n2.append( i1 )
return map
def find_path ( words,w1,w2 ):
i = [w[0] for w in words].index( w1 )
front,done,res = [i],{i:-1},[]
while front :
i = front.pop(0)
word,next = words[i]
for n in next :
if n in done : continue
done[n] = i
if words[n][0] == w2 :
while n >= 0 :
res = [words[n][0]] + res
n = done[n]
return ' '.join( res )
front.append( n )
return '%s can not be turned into %s'%( w1,w2 )
for w in ('boy man','girl lady','john jane','alien drool','child adult'):
print( find_path( cache( build_map,load_dico( dico_url )),*w.split()))

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lower: procedure; parse arg a; @= 'abcdefghijklmnopqrstuvwxyz'; @u= @; upper @u
return translate(a, @, @u)

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Task/Word-ladder/REXX/word-ladder-2.rexx Normal file
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/*REXX program finds words (within an identified dict.) to solve a word ladder puzzle.*/
parse arg base targ iFID . /*obtain optional arguments from the CL*/
if base=='' | base=="," then base= 'boy' /*Not specified? Then use the default.*/
if targ=='' | targ=="," then targ= 'man' /* " " " " " " */
if iFID=='' | iFID=="," then iFID='unixdict.txt' /* " " " " " " */
abc= 'abcdefghijklmnopqrstuvwxyz' /*the lowercase (Latin) alphabet. */
abcU= abc; upper abcU /* " uppercase " " */
base= lower(base); targ= lower(targ) /*lowercase the BASE and also the TARG.*/
L= length(base) /*length of the BASE (in characters). */
if L<2 then call err 'base word is too small or missing' /*oops, too small*/
if length(targ)\==L then call msg , "target word isn't the same length as the base word"
call letters /*assign letters, faster than SUBSTR. */
#= 0 /*# of words whose length matches BASE.*/
@.= /*default value of any dictionary word.*/
do recs=0 while lines(iFID)\==0 /*read each word in the file (word=X).*/
x= lower(strip( linein( iFID) ) ) /*pick off a word from the input line. */
if length(x)\==L then iterate /*Word not correct length? Then skip. */
#= # + 1; @.x= 1 /*bump # words with length L; semaphore*/
end /*recs*/ /* [↑] semaphore name is uppercased. */
!.= 0
say copies('─', 30) recs "words in the dictionary file: " iFID
say copies('─', 30) # "words in the dictionary file of length: " L
say copies('─', 30) ' base word is: ' base
say copies('─', 30) 'target word is: ' targ
rung= targ
$= base
do f=1 for m; call look; if result\=='' then leave /*Found? Quit.*/
end /*f*/
say
if f>m then call msg 'no word ladder solution possible for ' base " ──► " targ
do f-2; $= base; !.= 0 /*process all the rungs that were found*/
do forever; call look; if result\=='' then leave /*Found? Quit.*/
end /*forever*/
end /*f-2*/
call show words(rung)
exit 0 /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
msg: say; if arg()==2 then say '***error*** ' arg(2); else say arg(1); say; exit 13
show: say 'a solution: ' base; do j=1 to arg(1); say left('',12) word(rung,j); end; return
letters: do m=1 for length(abc); a.m= substr(abc, m, 1); end; return
/*──────────────────────────────────────────────────────────────────────────────────────*/
look: procedure expose @. !. a. $ abc base L rung targ search; rungs= word(rung, 1)
$$=; rung#= words(rungs)
do i=1 for words($); y= word($, i); !.y= 1
do k=1 for L
do n=1 for 26; z= overlay(a.n, y, k) /*change a letter*/
if @.z=='' then iterate /*Is this not a word? Then skip it. */
if !.z then iterate /* " " a repeat? " " " */
if z==rungs then rung= y rung /*prepend a word to the rung list. */
if z==rungs & rung#>1 then return z /*short─circuit. */
if z==targ then return z
$$= $$ z /*append a possible ladder word to $$*/
end /*n*/
end /*k*/
end /*i*/
$= $$; return ''

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Task/Word-ladder/Racket/word-ladder.rkt Normal file
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#lang racket
(define *unixdict* (delay (with-input-from-file "../../data/unixdict.txt"
(compose list->set port->lines))))
(define letters-as-strings (map string (string->list "abcdefghijklmnopqrstuvwxyz")))
(define ((replace-for-c-at-i w i) c)
(string-append (substring w 0 i) c (substring w (add1 i))))
(define (candidates w)
(for*/list (((i w_i) (in-parallel (string-length w) w))
(r (in-value (replace-for-c-at-i w i)))
(c letters-as-strings)
#:unless (char=? w_i (string-ref c 0)))
(r c)))
(define (generate-candidates word.path-hash)
(for*/hash (((w p) word.path-hash)
(w′ (candidates w)))
(values w′ (cons w p))))
(define (hash-filter-keys keep-key? h)
(for/hash (((k v) h) #:when (keep-key? k)) (values k v)))
(define (Word-ladder src dest (words (force *unixdict*)))
(let loop ((edge (hash src null)) (unused (set-remove words src)))
(let ((cands (generate-candidates edge)))
(if (hash-has-key? cands dest)
(reverse (cons dest (hash-ref cands dest)))
(let ((new-edge (hash-filter-keys (curry set-member? unused) cands)))
(if (hash-empty? new-edge)
`(no-path-between ,src ,dest)
(loop new-edge (set-subtract unused (list->set (hash-keys new-edge))))))))))
(module+ main
(Word-ladder "boy" "man")
(Word-ladder "girl" "lady")
(Word-ladder "john" "jane")
(Word-ladder "alien" "drool")
(Word-ladder "child" "adult"))

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Task/Word-ladder/Raku/word-ladder.raku Normal file
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constant %dict = 'unixdict.txt'.IO.lines
.classify(*.chars)
.map({ .key => .value.Set });
sub word_ladder ( Str $from, Str $to ) {
die if $from.chars != $to.chars;
my $sized_dict = %dict{$from.chars};
my @workqueue = (($from,),);
my $used = ($from => True).SetHash;
while @workqueue {
my @new_q;
for @workqueue -> @words {
my $last_word = @words.tail;
my @new_tails = gather for 'a' .. 'z' -> $replacement_letter {
for ^$last_word.chars -> $i {
my $new_word = $last_word;
$new_word.substr-rw($i, 1) = $replacement_letter;
next unless $new_word ∈ $sized_dict
and not $new_word ∈ $used;
take $new_word;
$used{$new_word} = True;
return |@words, $new_word if $new_word eq $to;
}
}
push @new_q, ( |@words, $_ ) for @new_tails;
}
@workqueue = @new_q;
}
}
for <boy man>, <girl lady>, <john jane>, <child adult> -> ($from, $to) {
say word_ladder($from, $to)
// "$from into $to cannot be done";
}

43
Task/Word-ladder/Ruby/word-ladder.rb Normal file
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require "set"
Words = File.open("unixdict.txt").read.split("\n").
group_by { |w| w.length }.map { |k, v| [k, Set.new(v)] }.
to_h
def word_ladder(from, to)
raise "Length mismatch" unless from.length == to.length
sized_words = Words[from.length]
work_queue = [[from]]
used = Set.new [from]
while work_queue.length > 0
new_q = []
work_queue.each do |words|
last_word = words[-1]
new_tails = Enumerator.new do |enum|
("a".."z").each do |replacement_letter|
last_word.length.times do |i|
new_word = last_word.clone
new_word[i] = replacement_letter
next unless sized_words.include? new_word and
not used.include? new_word
enum.yield new_word
used.add new_word
return words + [new_word] if new_word == to
end
end
end
new_tails.each do |t|
new_q.push(words + [t])
end
end
work_queue = new_q
end
end
[%w<boy man>, %w<girl lady>, %w<john jane>, %w<child adult>].each do |from, to|
if ladder = word_ladder(from, to)
puts ladder.join " → "
else
puts "#{from} into #{to} cannot be done"
end
end

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Task/Word-ladder/Swift/word-ladder.swift Normal file
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import Foundation
func oneAway(string1: [Character], string2: [Character]) -> Bool {
if string1.count != string2.count {
return false
}
var result = false
var i = 0
while i < string1.count {
if string1[i] != string2[i] {
if result {
return false
}
result = true
}
i += 1
}
return result
}
func wordLadder(words: [[Character]], from: String, to: String) {
let fromCh = Array(from)
let toCh = Array(to)
var poss = words.filter{$0.count == fromCh.count}
var queue: [[[Character]]] = [[fromCh]]
while !queue.isEmpty {
var curr = queue[0]
let last = curr[curr.count - 1]
queue.removeFirst()
let next = poss.filter{oneAway(string1: $0, string2: last)}
if next.contains(toCh) {
curr.append(toCh)
print(curr.map{String($0)}.joined(separator: " -> "))
return
}
poss.removeAll(where: {next.contains($0)})
for str in next {
var temp = curr
temp.append(str)
queue.append(temp)
}
}
print("\(from) into \(to) cannot be done.")
}
do {
let words = try String(contentsOfFile: "unixdict.txt", encoding: String.Encoding.ascii)
.components(separatedBy: "\n")
.filter{!$0.isEmpty}
.map{Array($0)}
wordLadder(words: words, from: "man", to: "boy")
wordLadder(words: words, from: "girl", to: "lady")
wordLadder(words: words, from: "john", to: "jane")
wordLadder(words: words, from: "child", to: "adult")
wordLadder(words: words, from: "cat", to: "dog")
wordLadder(words: words, from: "lead", to: "gold")
wordLadder(words: words, from: "white", to: "black")
wordLadder(words: words, from: "bubble", to: "tickle")
} catch {
print(error.localizedDescription)
}

41
Task/Word-ladder/Wren/word-ladder.wren Normal file
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import "io" for File
import "/sort" for Find
var words = File.read("unixdict.txt").trim().split("\n")
var oneAway = Fn.new { |a, b|
var sum = 0
for (i in 0...a.count) if (a[i] != b[i]) sum = sum + 1
return sum == 1
}
var wordLadder = Fn.new { |a, b|
var l = a.count
var poss = words.where { |w| w.count == l }.toList
var todo = [[a]]
while (todo.count > 0) {
var curr = todo[0]
todo = todo[1..-1]
var next = poss.where { |w| oneAway.call(w, curr[-1]) }.toList
if (Find.first(next, b) != -1) {
curr.add(b)
System.print(curr.join(" -> "))
return
}
poss = poss.where { |p| !next.contains(p) }.toList
for (i in 0...next.count) {
var temp = curr.toList
temp.add(next[i])
todo.add(temp)
}
}
System.print("%(a) into %(b) cannot be done.")
}
var pairs = [
["boy", "man"],
["girl", "lady"],
["john", "jane"],
["child", "adult"]
]
for (pair in pairs) wordLadder.call(pair[0], pair[1])